Effects of masting on seedling establishment of a rodent-dispersed tree species in a warm-temperate region,northern China

Masting is an evolutionary strategy used by plants to promote seed survival and/or seed dispersal under animal predation,but its effects on seedling establishment in field condition are rarely tested by long-term experiments incorporating combined effects of seed and animal abundance.Here,we tracked seed production,rodent-mediated seed dispersal,and seedling establishment in Armeniaca sibirica from 2005 to 2014 in a warm-temperate forest in northern China,and examined the effects of seed abundance and per capita seed availability on seed fate and seedling recruitment rate.Our results showed that seed abundance or per capita seed availability generally benefited the seedling recruitment of A.sibirica through increasing dispersal intensity,supporting predator dispersal hypothesis.However,seedling recruitment showed satiated or even dome-shaped association with per capita seed availability,suggesting the benefit to trees would be decreased when seed abundance were too high as compared to rodent abundance(a satiated effect).Our results suggest that the predator dispersal and satiation effects of masting on seedling recruitment can operate together in one system and conditionally change with seed and animal abundance.

How does the 120-year cycle mast seeding of dwarf bamboo affect the rodent population?

Background:In 2017,large-scale flowering,seeding,and dying events of dwarf bamboo(Sasa borealis)occurred in a wide range in central Japan for the first time in 120 years.This phenomenon of S.borealis,like the mast seeding of trees,could be expected to provide a large amount of food for seed-eating rodents and gradually affect their ecology and population dynamics.We captured rodents in survey plots in a secondary broad-leaved forest with the phenomenon from 2018 to 2019 to investigate the species,the number of individuals,growing stage,sex,and body mass.In addition,we also compared the capture data for 2 years(2018–2019)with that for the mast seeding year(2017)and 6 years before it(2011–2016).Results:The mast seeding of S.borealis greatly increased the population size of rodents,especially Apodemus speciosus and A.argenteus.Conversely,Eothenomys smithii did not show such an increase.Most of the captured rodent individuals were already adults at the time of new capture,and the proportion of male juveniles was extremely low.These results suggest that the mast seeding of S.borealis created unusually rich food availability for the population concentration of rodents due to their immigration.However,body mass was not significantly different before and after the mast seeding.In addition,the increased populations of the two Apodemus species did not decline 2 years after the S.borealis masting,contrary to the previously reported decrease of rodent populations after tree masting.Conclusions:Our results indicate that the mast seeding of S.borealis affected the population dynamics of Apodemus species over a long time and their individual composition of different growth stages.However,it did not affect their body mass.